I came for the cogs, stayed for the cog-puns. I felt difficulty ramped up a little too slowly, I almost stopped playing pretty early, as the first 20 puzzles were basically just 1 of 2 things (either - just place a straight line, or just pack tightly) with no strategy required. Levels definitely got interesting beyond there. I appreciate the level selector and marking where new mechanics are unlocked, that's great for getting a better feel for the game! I wished I had an easier way to undo (a hotkey, perhaps), as I often found myself wanting to try re-placing a single cog a number of times to see if it'll line up... Music was nice and didn't get in the way. Well done!